11/5 Embriology of the Head Flashcards
What is a deffect of nerual tube closure at the head?
Anecephaly
Form most of the facial bones
The neural crest cells
the three origins of the bones of the skull;
The neural crest cells, the paraxial and lateral plate mesoderm.
the part of the skull that arises from the neural crest cells:
the frontal part (frontal; nasal; lacrimal; zygomatic; maxilla; incisive; mandible), the lower sids (Sphen. and Sq. temp.) and the hyoids
what bones are derived from the paraxial mesoderm (somites and somitomeres)
the back of the skull (parietal, pet. temp.; occipitals;)
The somites that provide the paraxial mesoderm for the back of the skull:
occipital somites and somitomeres
arises from a number of paired cartilage elements that fuse and ossify
the base of the skull.
which cartilage elements of the head come from neural crest and which are from paraxial mesoderm?
those in front of the rostral limit of notochord are from n.c. and posterior from paraxial mesoderm.
What etablishes the cranial to caudal segmentation of the pattern of the body?
the Hox code!
How does the cranial to caudel pattern of the somites get carried ventrally?
Migrating crest cells carry segmental information ventrally.
How can we anticipate the related symptoms of a syndrome based on N.C. cells
the structrues produced by crest from the same location can all reflect a common defect.
The Cranial nerve of Brachial arch 1
The Trigeminal nerve (V-3) (mastication); and a little of Geniculate (VII) (facial expression).
The Cranial nerve of Brachial arch 2
CN VII (facial expression), and IX (pharynx and larynx)
what are the minor (2) and major contributor to the head development?
lateral plate mesoderm and the paraxial mesoderm and the N.C. cells
part of the skull that comes from the lateral plate mesoderm
the laryngeals
The Cranial nerve of Brachial arch 3
CN IX (pharynx and larynx)
The Cranial nerve of Brachial arch 4
Vagus (CN X) (pharynx and larynx)
primary contributers to the face from the brachial arches
arches 1 and 2
The bone from the arch 1
(meckel’s cartilage): maxilla, mandible, temporal bone, two middle ear ossicles (malleus, incus)
the bone from the arch 2
(Reichert’s cartilage) one middle ear ossicle (stapes). syloid process, stylohyoid ligament, and lesser horn and part of the body of hyoid
the bone from the arch 3
greater horn and part of body of hyoid
arch 4 bone
thyoid cartilage
arch 6 bone
cricoid cartilage
the origin of the outer ear?
the first and second arch derivatives
how can the outer ear indicate a problem with cranial nerual crest cells)
The same nerual crest cells can that lead to the ear defects also contribute to many other structures (heart inner ear etc.)